I tried using a SIP line with another service provider with no MOH on theirs lines.

The result: no MOH on the line.

What I would like to know is if it's possible to overide the MOH from the service provider. All the configs I tried with SLA and SPA-9000 always end up with hearing the MOH from the service provider. Our test show that if I remove the SLA, all work properly (I hear the MOH from spa-9000).